\\[-1.8ex] Soil Heterogeneity & $-$0.036$^{*}$ & $-$0.038$^{*}$ & $-$0.053$^{**}$ & $-$0.049$^{**}$ \\ 
  & (0.021) & (0.021) & (0.025) & (0.024) \\ 
\\[-1.8ex] 
Observations & 7,558 & 7,558 & 2,038 & 2,038 \\ 
R$^{2}$ & 0.614 & 0.615 & 0.527 & 0.541 \\ 
